If you're always thinking this way when you're not occupied with something else, then yes, I'd definitely say that is a sign you're still clinically depressed. Do these thoughts just "pop up" and are of a theoretical nature (i.e. you're pondering about the meaning of it all, but don't emotionally feel like commiting suicide) or do you really still feel completely hopeless and equally suicidal as you did before taking antidepressants (or even more so)?
Either way, I think you should definitely talk to your therapist or psychiatrist about it. Some antidepressants can have heightened suicidality as a side effect.